I just noticed, in the OP’s first post, the fourth picture shows a bit of the engraved stock shield. It appears to be engraved by the same hand that engraved the shield on my Delgrego/Runge upgraded CHE 28ga. This makes me believe that Delgrego and Robert Runge had a hand in at least the stock of the OP’s gun.
The first picture is my gun. The 2nd (double click it to enlarge it) is the OP's

Chuck, what I said was "The serial number 131429 is not on the list of 28-gauge guns from the records, published in The Parker Story, page 1005." As much of page 1005 as I could get on my scanner --

Attachment 129536

Without taking anything away from the TPS authors, the time involved in searching the available books didn't permit the necessary scrutiny the research director afforded me. When I acquired 99687, the database said it found no records. This made no sense to me as 99686, and 99688 were listed in the serializations book (99686 is listed as a 28ga) The research director carefully examined the books and found that a red pencil mark obscured the numeral 7, but close examination showed it was a 28ga. The records further showed it was ordered with 99686, as an identical pair.

The gun was a 28 that was sleeved and kept as a 28g. Who knows why, especially since the gun started out as fluid steel. I have seen it before.

You’re lucky to have a Parker 28 gauge. Show us the top end of the barrels and a straight on pic of where the tubes touch. Learning to use the photo posting feature on this forum would help a lot.

I use both with equal results. The problem is when you just copy and paste in the web address of the photo. It comes out as a link like these. If you click on the Imgur picture and then click on the copy for BBS button, it appears as a linked photo in the post, just like the uploaded photos. I use Imgur here when I already have them on Imgur. It makes it easier position and edit the images.